Voiced telecommunication systems have evolved from telephones that were originally connected directly together in pairs to trunked exchange systems and from there to completely digital systems where communication is facilitated through exchange of data packets over a number of interconnected networks. For example, Voice Over IP (VOIP) telephony uses internet protocol over wired and wireless networks, which may be public, secure, or a combination of the two.
Additional communication modes such as video, instant messaging, application or data sharing have also proliferated in recent years with the availability of diverse types of communication networks and devices capable of taking advantage of various features of these networks. Some more recent systems (e.g. unified communication systems) take advantage of capabilities of modern networks and computing devices bringing together different communication networks and providing until now unavailable functionality such as combining various modes of communication, user defined routing mechanisms, and so on. In such systems, a network of servers manages end devices capable of handling a wide range of functionality and communication while facilitating communications between the more modern unified communication network devices and other networks (e.g. PSTN, cellular, etc.).
In a system that supports multiple forms of communication, it is important for administrators to be aware of the quality of experience delivered to the users by the system. This enables the administrators to adjust the configuration of the system as needed when the quality deteriorates. Quality of experience may degrade generally due to problems in the network(s) or problems in the computing devices through which the media travels. If the problem happens to be on the machines, it is difficult for the administrators to narrow down and focus on the problematic ones in a system with a large number of devices. Determination of the source of the problem requires a systematic approach to find the worst performing device(s).